A history of 10 or more lifetime sexual partners is linked to a heightened risk of being diagnosed with cancer, reveals research published online in the journal BMJ Sexual & Reproductive Health.
And among women, a higher number of sexual partners is also linked to heightened odds of reporting a limiting long term condition, the findings indicate.
Few studies have looked at the potential impact of the number of sexual partners on wider health outcomes.
To try and plug this knowledge gap, the researchers drew on information gathered for the English Longitudinal Study of Ageing (ELSA), a nationally representative tracking study of older adults (50+) living in England.
In 2012-13, participants were asked how many sexual partners they had had. Complete data were provided by 5722 of the 7079 people who responded to this question: 2537 men and 3185 women. Responses were categorised as 0-1; 2-4; 5-9; and 10 or more sexual partners.
Participants were also asked to rate their own health and report any long standing condition or infirmity which impinged on routine activity in any way.
Other relevant information obtained included: age; ethnicity; marital status; household income other than a pension; lifestyle (smoking, drinking, physical activity); and presence of depressive symptoms.
The average age of participants was 64, and almost three out of four were married. Some 28.5% of men said they had had 0-1 sexual partners to date; 29% said they had had 2-4; one in five (20%) reported 5-9; while 22% reported 10 or more.
The equivalent figures for women were: just under 41%; 35.5%; just under 16%; and just under 8%.
In both sexes, a higher number of sexual partners was associated with younger age, single status, and being in the highest or lowest brackets of household wealth.
Those who reported a higher tally of sexual partners were also more likely to smoke, drink frequently, and do more vigorous physical activity on a weekly basis.
When all the data were analysed, a statistically significant association emerged between the number of lifetime sexual partners and risk of a cancer diagnosis among both sexes.
Compared with women who reported 0-1 sexual partners, those who said they had had 10 or more, were 91% more likely to have been diagnosed with cancer.
Among the men, those who reported 2-4 lifetime sexual partners were 57% more likely to have been diagnosed with cancer than were those who reported 0-1. And those who reported 10 or more, were 69% more likely to have been diagnosed with the disease.
While the number of sexual partners was not associated with reported long standing conditions among the men, it was among the women.
Women who reported 5-9 or 10+ lifetime sexual partners were 64% more likely to have a limiting chronic condition than those who said they had had 0-1.
This is an observational study, and as such, can't establish cause. Nevertheless, the findings chime with those of previous studies, implicating sexually transmitted infections in the development of several types of cancer and hepatitis, suggest the researchers.
They didn't obtain information on the specific types of cancer participants reported, but speculate: "...the heightened risk of cancer might be driven by those types known to be associated with [sexually transmitted infections]."
And they suggest that enquiring about the number of sexual partners might complement existing cancer screening programmes by helping to identify those at risk, if further research can establish a causal association between the number of sexual partners and subsequent ill health.
But an explanation for the gender difference in long term condition risk remains "elusive," they write, especially given that men tend to have more lifetime sexual partners than women, while women are more likely than men to see a doctor when they feel ill, so potentially limiting the associated consequences for their long term health.
Peer reviewed? Yes
Evidence type: Observational
BMJ Sexual & Reproductive Health